Sound recording and reproducing system



Sept. 4, 1945. c. L. PRICE I 2,384,131

SOUND RECORDING AND REPRODUCING SYSTEM Filed Jan. 10, 1944 2Sheets-Sheet 1 19 lforn e5.

Sept. 4, 1945. c. PRICE 2,384,131

SOUND RECORDING AND REPRODUCING SYSTEM I Filed Jan. 10, 1944 2Sheets-Sheet 2 V l 75/ 7 II lmrmmuuumuluummmnwuumuuumnu v ll/11111111null/1m.n n 1 nu mnmmmu I Patented Sept. 4,1945

cummi L. Price, Oakland, Calif. I Application January 10, 1944, SerialNo. 517,782

6 Claims. (Cl.,l79. '0.3)

This invention, a sound recording and reproducing system, is animprovement over existent systems such as the molded plastic andsoundon-film types, in that the highest degree of fidelity is attainablewith an absolute minimum in size, volume and weight 'of the recordings.

With the conventional sound-on-fllm method of recording and reproducingsound, about 60 or more feet'of 35 mm. film, and corresponding lengthsof 16 mm. and 8 mm. film is required to record and reproduce each minuteof program.

The decreased lengths with 16 mm. and 8 mm.

film are not due to any desire or anticipation of reducing the length ofthe recording or sound track, but develops through amatter of necessity,the desire being merely to reduce thesize of the frames which in turnrequires thatthe portion of the sound track included in a 35 mm. framemust be reduced along with the picture to fit in the smaller frame. Withmy invention a one-minute program of equal fidelity is reproduced fromonly 2% feet of film, and twenty-five or more recordings or differentsound tracks can be recorded on an 8 mm. film.

Plastic records are bulky-and heavy, very easily damaged, anddeterioratefairly rapidly with repeated playing, while with my type ofrecord-' ing, extremely light weight, minimum bulkiness, and freedomfrom damage and deterioration are prevalent. a

With my invention, spiral recordings can be made on 35 mm. film to playfor the same length of time as standard disc records. If desired, thesespiral records can be produced in spaced relation on a continuous stripof 35 mm. film and thus used with suitable selecting mechanism in thereproducing unit, or the recordings'may be separated into individualrecords.

The recordings are preferably reproduced from the original recording ormatrix, to a scale conforming to the resolving power of the film to beused, and then preferably projected to a size about equal to that of theoriginal record, with the enlarged image of the sound track in lightandshadow interceptedby a suitable photo-cell, followed by suitableamplification and translation into sound.

The objects and advantages of the invention are as follows:

First, to provide a system of sound reproduction in which the greatestdegree of fidelity it attainable'.

Second, to provide a system in which the recordings are of minimum sizeand weight.

Third, to provide a system in which the recordings are photographicallyformed from a matrix having a normal'size sound track, on a relativelysmall area or length of film, to -a greatly reduced scale. a

Fourth, to provide a system in which an original sound track ormatrixismadeby conventional sound-on-film recording apparatus, and recordingsmade therefrom to a greatly reduced scale.

Fifth, to provide a system in which the recordings are produced from' anormal sound track. by photo-copying to a greatly reduced scale, on atransparent base photographic emulsion followed by suitable development.1

Sixth, to provide a system in which .soundis normally convertedlntophotographic densities to form a sound track of normal size, andproducing recordings for use by photographingsaid sound record or trackto a scale established by the resolving power of the emulsion used.

Seventh, toreproduce sound from said recordings of greatly reducedscale. by projecting a traveling image of the sound track through anoptical system to a size approximating thatof the original sound track,photometrically intercepting the enlarged light and shadow image,amplifying the effects of the intercepted light and shadow fluctuations,and' translating the amplified fiuctuations into sound waves.

Eighth, to provide a sound reproducing system the photo-sensitive means,and translating the amplified fluctuations into sound waves.

Other objects and advantages of the invention will become apparent asthe following description is read on the accompanying drawings, inwhich: Fig. 1 is a fragmentary plan view of a matrix with a spiral soundtrack formed thereon through conventional sound-on-film recording means.r

Fig. 2 is a full size plan view of one of the recordings as made from ,aspiral matrix,.on 35 mm. film, with the sound track only illustrativelvindicated on a greatly enlarged scale.-

Fig. 3 is a side elevation of the reproducing unit for the spiral formof soundtrack; and is partly shown in section. i

Fig. 4 is a front elevation of Fig. 3.

Fig. 5 is a plan view of the recording holder I j of copying ribbonmatrices to a reduced accordance with this invention.

Fig; 6 is a seetiontaken on line 8-6 of Fig. 5. Fig. 7 isa modificationof the matrix fragmentarlly shown, and indicating a multiplicity ofsound tracks in parallel.

Fig. 8 illustrates a modification of the feeding 1 means, for feedinglineal or ribbon recordings, and includes means for adjusting the recording transversely for selection of the respective sound tracks fordifferent programs, and is taken on a line' 04 of Fig. 9.

Fig'. '9 is a front elevation of the reproducing unit for ribbon typerecordings. V

Fig. 10 is a side elevation of Fi 9.

Fig. 11 is a fragmentary view of an 8 mm. ribbon type recording, with aplurality of sound tracks in'parallel. a

Fig. 12 diagrammatically illustrates the-method scale in f The matrixFig. l, is preferably formed on a circular disc ofmoisture proof basesupported mission;

photographic emulsion, and may be either, developing paper, plate, orfilm; plate or film being preferable because paper would necessitatecopying to the reduced size by reflection, while a 1 plate or film iscorrectly copied through trans- During the recording process, which iscar- 1 riedout by conventional sound-on-film recording equipment, thefilm, instead of being fed Zineally, is fed, spirally throughsimultaneous 1 rotation and diametric adjustment, so that the i soundtrack It will be formed as a continuous spiral from the periphery lltoward the axis l2,

; with a clear space llleft between convolutions. Processing is carriedout byany of the conventional processes, thecircular form permittingrotational agitation in the processing solutions,

thereby avoiding edge wash as would occur with rectangular sheets,assuring uniformityin proc essing even with variable density types ofsound tracks.

The correctly processed matrix is copied through conventional methods,such as a reducingcamera, .on a small section or short length of filmhaving very high resolving power, such of about.24 mm., (the space llbetween the 1 as'Micro-file or Graticular film, with a two-foot diametermatrix readily reduceable to a diametersprocketholes II in 35 mm. film),as shown in Fig. 1

2 though other sizes of film can be used, and the recording made largeror smaller,-as may be desired or required. There is one distinct ad- 1vantagein having the recording as small as possible; it obviates thenecessity for a compara-j tively. long focus lens, or for a transversefeed} for a short focus lens, for, the reproducing system.

In making these miniature recordings, the film applied to the clear endsor sides, with the title or number simultaneously indicating by its cor-1 rect reading position the correct placement of the recording in thereproducing unit. Such equip ment .and devices are well known in the artand are therefore believed to require no description.

In connection with the production of these miniature or microscopicrecordings, it might be mentioned that Micro-file film is capableofresolving about 230 lines per mm., while Graticular film is capable ofresolving about 500 lines per mm. The resolving powers of these filmsare therefore respectively about i and 2a. Thus, if the matrix is 24inches in diameter with the pitch P of the spirals equal to /6 inch, thepitch p of the spirals on a 35 mm. reduced recording will be about .005inch or 127a, with the sound track having a transverse width of about.0025

inch or 63 and the space between the spirals also,.0025 inch or 6311..This is equal to about sixteen: times the resolving 'power'of-Micro-file film, and thirty-two times that of Graticular film, a veryample margin. a

With conventional recording and reproducing methods, each minute ofprogram requires at least feet of 35 mm. film, and corresponding lengthsof 16 mm. and 8 mm. film, though, as previously stated, this reductionis made to 16 or 8 mm. film only as a matter of necessity, to condensethe relative proportion of sound track within the space occupied by oneframe or picture. With my system only 2 /2 feet of Graticular film, or 5feet of Micro-film, is required for a recording of similar frequency andfidelity, and it is easily possible to record twenty-fiv sound tracks inparallel on a strip of 8 mm. film, with only 37 feet being required forfifteen-minute recordings. The matrix can be'made on a comparativelywide ribbon, three or four inches, if a large number of sound tracks'areto be produced on the same miniature recording. However,from one toeight sound tracks canbe recorded on '35 mm, film, ard several-of thesecan be recorded to the reduced scale on a single strip of 8 mm. film.Obviously, this system is not limited to 8mm. film. Any desired size canbe used. .The reproducing unit forthe spiraltype of recording isillustrated in its simplest form as comprising .an enlarging unittogether with suitable feeding means, which broad statement appliesequally. to the lineal or ribbon type of recording.

A projection lamp i8 is housed in a suitable lamp housing I 9 which atits lower end has a very narrow slit 20 of sufilcient length to extendover the cumulative recorded width of the series of parallel recording,or for spiral recordings,

across the radial width of the spirals which would be somewhat less thanthe radius of the recording for spiral'sound tracks, and which in thecase of 35 mm. recordings 2! would be about 1 cm., as

there would be no sound track close .to the axis.

It is understood that a suitable condenser system.

or diffusion screen, or both, may be incorporated in the illuminatingunit. a

The holder and turntable for the spiral type of recording consists of agear 22 having an axial passage 23 equal in diameter to the diameter ofthe recording, and has combined locators and spring clips 24 with thelocating shouldersspace'd apart a distance exactly equal to the widtheofthe recording blank. An indexing'button 28 is receivable'in the hole I 6for accurately locating the recording lengthwise; the recording beingslipped underthe clips and pushed forward until the hole. snaps over thebutton/261v Projecting from the underside of this gear is a bearingcollar 21 which rotatably fits in a gib bearing 28 which is'integralwith the arm 29 which extends from the shaft bearing v30 which ismounted on the upright 31. This bearing 28 has a lens barrel 32 locatedeccentrically and in registry with the light beam slit 20, and hasasuitable lens combination 33 mounted in the lens 2,384,131 barrel. Theprojection lamp housing is mounted in a head 34 which. is hinged at 35so that it can conveniently be tilted out of the way to provide accessto'the recording holder.

Mounted in bearings 16 on the base 31 is a feed screw 30, and inparallel relation to the feed screw is a guide rod 30 on which isslidably mount ed one end of a support which has a half nut 4| formed atits other end to threadedly cooperate with the screw 38, and a handle'42 projects beyond the half nut for manual lifting of the half nut outof engagement with the screw 18 so that the support can be slidablyreturned to its starting position.

Mounted on the support "is a photo-cell unit 43 which intercepts apredeterminedarea of one spiral of projected rays such as 44 of theprojected light and shadow image of the sound track on the recording,and transmits the results of fluctuations in light intensity or volumeof the traveling projected sound track to a suitable amplifier II andthence to a sound translating device ll; the structures, functions, andoperations of which are well known in the art and'are conventionalequipment.

The screw 38 may have a pitch equal to the pitch of the projectedspirals, under, which conditions the rotational speedsof the screw 38and the recording holder 22 are equal, being driven by a very slow speedmotor 41, or by a motorwith suitable speed reducer. As shown, the screwis driven direct, while the recording holder is driven from the screwthrough the miter gears 48, shaft ll, and gear Bil.

Obviously, the shorter the focal length of the lens II, the less will bethe distance between the recording It and the photo-cell 43. Since thelight passes only through an extremelynarrow slit, the focal length ofthe lens can be about equal to the length of theslit, in the case of 35mm.

film about to 12 mm., with the distance from lens to, photo-cell beinganywhere from five to thirty-five focal lengths.

In making the matrix, the blank can be rotated similarly to that of therecording in the reproducing unit just described, coupled with adiametric feed to produce the spiral sound track, and with the recordingbeam of vibratory mirror in a definite and fixed location.

, For ribbon recordings on 8, 16 or 35 mm. films,

the matrixmay be made as illustrated in Fig. .7,

with one, or with a plurality of different sound tracksin parallel. Thismatrix is then copied to a reduced scale indicated in Fig. 11 asdiagrammatically illustrated in Fig. 12, in which sets .image of whichis projected by the lens 58 through the slit 0! in the pressure plate 60to the photo-sensitive emulsion II to a greatly reduced scale; theroller 0| being driven by suitable driving means, and in turn drivingthe roller 52 at a greatly reduced speed as indicated by the belt BI andsheaves l2 and II.

The reproducing unit for ribbon type record-' ings consists of a feedplate or platen 84 which has a slit 0! through which the image of thesound track It is projected through the lens 61 to the interceptor orphoto-cell 88 as indicated at 00; the sound track, lens, and interceptorbeing in perfect alignment and the lens. Properly focused.

- This feed plate is slidably mounted in a support II as indicated at Hand is-transversely'adiustable to bring the respective sound tracks,such as 00 and II in perfect registry with the axis of the lens and withthe interceptor. by means of spaced screws" which are rotatable inbearings I4 on the support 10, and threadedlyoperable in threadedpassages formed in the upright 15 on the platen 04. These two screws arecoupled together for synchronous operation as indicated at II, by meansof the knob or dial I1 which is provided with calibrations I. forcoordination with the pointer ll, Therecording I is perfectly alignedbetween'the shoulders I and 01, ll being formed as a slot having a topwall functioning as a hold-down for the one edge of the recording; whilethe other side is held down and fed by suitable means such as thetoothed rollers It and I4 and encompassing,

pierced band 8|, the teeth onthe rollers being sufiiciently long to passthrough the band and engage the sprocket perforations It in the ribbonfor positive driving-of the recording. The respective rollers 03 and arefixed on the respective shafts I! and 80 which are rotatable in tegralwith the support II.

A suitable driv is provided and as illustrated" The interceptor orphoto-cell is connected in H circuit with a suitable amplifier I! andsound translating unit 40.

The support 10 is integral with a standard II and integral base N onwhich the interceptor is moun in a fixed position. x

As in cated at II, the sound track is enlarged into a traveling lightand shadow image, to a size preferablyabout equal tp that of the origi-,nally recorded sound track at the point I where the light and shadowimage is intercepted by the photo-cell. The speed of travel and the areaof the intercepted light and shadow image is therefore approximatelyequal to that of the original recording. v

The correct speed of travel of the recording is governed preferably bythe resolving 'power'of the emulsion used. 'Graticular film iscapable ofresolving about 500 lines per mm. which isequiv- I, alent to about12,750 lines per inch. On this basis, the correct for a 6000 cycle trackwould be about 12- mm. or approximately tiinch per second, while forextreme fidelity at 10,000 cycles per second the correct speed would beabout 20 mm. or approximately inch-per second. Micro-file film iscapable of resolving about 230 lines per mm., which is equivalent toabout 5,850 lines per inch. On the basis of 6000 cycles per second thecorrect speed would be about 26 mm. or approximately one inch persecond, and for 10,000 cycles per seconiabout 4-4 mm. or approximately1% inches per second.

The reduction from the matrix for Graticular riginal, thirty feed persecond.

film would be on th order of 24:1 to 36:1, and for Micro-file film about12:1 to 18:1, though any desired reduction not exceeding the previousmaximums could be used. Speedsand reductions for other types ofemulsions would be proportionate to their respective resolving powers.

In the case of Graticular film reduced to of the original matrix, thedistance between the w lens 82 or 1 and the interceptor 43 or 88 shouldpreferably be made equal to twenty-five focal lengths. In other words,the projection distance should be equal to the ratio of reduction plusone, multiplied by the focal lengthof the lens. However, this value maybe increased or decreased as desired. 7

It will be-noted that if the original sound track is recorded at alineal speed of 30 feet per second,

the recording made with a reduction of 24, then image of the sound trackat the point of interception will have the same lineal speed as the Iclaim:

enlarged 24 times, the traveling light and shadow 1. Sound reproducingapparatus comprising; I

a first support; a lens mounted on one side of said support and a sourceof projection illumination mounted on the other side; meansrotatablymounted on said firstsupport between said lens and said source ofprojection illumihation. for

supporting a disc-type photographic recording in the focal plane of saidlens; a second support in spaced relation to said first support; aphoto-cell located in the object plane of said lens and radiallyadjustable on said second, support; and driving means for driving saidmeans rotatably mounted at uniform speed and simultaneously radiallyadjusting said photo-cell at a speed '00- ordinated to the speed ofradial travel of the projected image of the sound track on the disctyperecording.

2. A structure as defined in claim 1; said means .rotatably mountedcomprising a ring gear peripherally supported and having means forperipherally securing a disc-type recording thereon;

said driving means for radially adjusting said photo-cell comprising ascrew and a guide bar ".mounted on said second support in parallel and alens; means for supporting and rotating a disctype photographic soundrecording having a spiral sound track, in the focal plane of said lens,

3. Sound reproducing apparatus comprising;

and means for illuminating said record; a photocell radially adjustablerelative to the axis of a projected image of said sound recording and2,sa4,1a1.. r 7

located in'the object plane of said lens; driving means for rotatingsaid means for supporting, and for radially adjusting said photo-cell incoordination with the speed of radial travel of the projected image ofthe sound track, and amplifying and sound translating means in circuitwith said photo-cell.

4. A structure as defined in claim 3; [said means for supportingcomprising; agear member which islight-transmitting throughout the areaof the soundtrack on the recording to permit passage of lighttherethrough to said lens; said means for radially adjusting saidphoto-cell comprising a guide bar and a screw mounted in parallel, and asupport slidable on saidbar and having a halfj-nut for threadedcooperation with said screw for adjusting and for convenientmanualreturn of said support slidable to a starting position, a gear forsaidscrew; said driving means including a gear connection to said gearmember and to said gear for saidscrew.

5. Sound reproducing apparatus for disc-type photographic recordingshaving a spiral sound track comprising; a lens; rotatable supportingmeans for supporting a recording in the focal plane of said lens andpermitting passage of light therethrough to said lens, and illuminatingmeans for said recording; a photocell located-in the object plane ofsaid lens, and driving means for said rotatable supporting means andtorsimultaneously adjusting said photo-cell in conformity with the speedof radial travel of the projected image of the sound track of therecording, and including means for manual return of said photo-cell tostarting position at will; and

amplifying and sound translating means in circuit with said photo-celli6; Sound reproducing apparatus for disc-type photographic recordingshaving a spiral sound between said lens and said source of illuminationand forming means for peripherally supporting a recording whilepermitting passage of light through the recorded area to said lens; abase; a slide bar and a screw mounted onwsaid base in parallel andradially relativeto the axis of said gear; a second support slidable onsaid bar and CLIFFORD n PRICE.

